BIG BALLISTICS
(v1.3 - June 2024)

NOTE: This is called "Big Ballistics" because it supports 'extreme' use cases such as 16-inch naval rifles. Virtually all online ballistics calculators are designed only to work with small arms use-cases.

The program source is based off an AppleBASIC program written in 1983 by W.J. Jurens and published in Warships International #1 (1984). It was rewritten into Python in 2018, and then into Javascript in 2020.

CLICK HERE FOR BACKGROUND ON ORIGINAL PROGRAM

NOTE: If you are using very short integration intervals AND simulating long trajectories, such as battleship guns at 30-45 degrees, with flight times of 60+ seconds, your browser may seem to hang. Just wait and it'll eventually cough out a table.

NOTE II: The code for the program is contained entirely within this HTML file; so you can download it for offline use on your own PC, or to extend/edit it yourself, without having to worry about tracking down dependencies from elsewhere.

Change Log

• v1.00 -- Initial Release.
• v1.01 -- Incremental changes to HTML forms; improved Form Factor Finder code to reduce program time for a run on Alaska 12"/50 rifles from 63.5~ seconds in v1-00 to 8~ seconds in v1-01. Added some drag table shape images. Worked a bit on weapons buttons.
• v1.02-1.06 -- Added Range Table generation and refactored code for ballistic range evaluation, bringing heavy naval guns down from 49.6 seconds to 5.5 seconds when firing to 35 km; needed for computing ballistic tables for big guns.
• v1.07 -- Incremental work on Range Table Codes to improve accuracy for very flat trajectory, high velocity (sabot rounds) gun tables (4000m code). Added Sub-Caliber Scaler. Added YAMATO and SUPER YAMATO presets. Placeholders added in UI for future advanced penetration codes.
• v1.1 -- Added Atmospheric Density Factor. Revised US Projectile Presets using the July 1950 "Handbook of Ballistic and Engineering Data for Ammunition"
• v1.2 -- Added code to automatically adjust integration interval based off projectile velocity as part of a general cleanup -- and further improved the range table/ballistic evaluation features to get accurate data with low drag very high velocity rounds such as long rod sabots.
• v1.3 -- Added special code (extend drag data to Mach 60 checkbox) to allow re-entry vehicle trajectories to be calculated as rough approximations.

Select Atmospheric Model: Vacuum U.S. Pre-1945 Atmosphere (Jurens Model) British Standard Atmosphere (Jurens Model) ICAO Standard Atmosphere 1964 (Jurens Model) US Standard Atmosphere 1976 (Good to 86 km) : Atmosphere Density Factor (1.01634 adjusts the ICAO Std Atmosphere to what the Germans used in WW2)

Select Gravity Model: Simplified Lunar Gravity Simplified Mars Gravity Simplified Earth Gravity Simplified Earth Gravity (Jurens Model) US 1976 Standard Atmosphere Gravity Model

PRE-GENERATED TEMPLATES these buttons are matched against known range tables to generate 99% valid form factors. these buttons contain reasonable assumptions, i.e. no firing table is known, but we assume that the shell form factor is similar to other smaller/larger caliber shells of the same design (example: Panzergranate 39). these buttons have valid basic properties (diameter, mass, muzzle velocity), but the drag factor and form factor are completely generic. these buttons are missing one (or more) validated basic properties and the drag factor and form factor are completely generic.
SMALL ARMS / MACHINE GUNS UK US GERMANY USSR TANK GUNS US UK German Modern Weapons	ANTI-AIRCRAFT / DUAL PURPOSE GUNS HEAVY GUNS NAVAL GUNS AERIAL BOMBS WW2 Bombs 1960s Mk 80 Series Bombs

MANUAL DATA INPUT Yellow boxes are secondary input fields; enter your data and hit enter, and they will automatically translate/convert into the primary input fields. : Projectile Diameter (mm) : Inches/Caliber (Proj. Diam.) : Centimeters (Proj. Diam.) : Projectile Mass (kg) : Pounds (Proj. Mass) : Grains (Proj. Mass) : Grams (Proj. Mass) Penetrator Data: : Penetrator Length (mm) : Penetrator Diameter (mm) : Penetrator Mass (kg) This data is used in complex penetration algorithms such as Lambert-Zukas, which require penetrator length and also in simple algorithms such as the Soviet "DeMarre" formula, so that APCR rounds where the subcaliber tungsten penetrator is surrounded by a full caliber aluminum windshield can be handled by them.	WEAPON SCALER This will calculate scaled masses for a larger or smaller shell of the same general shape. To use, you first load a hypothetical shell into the left-side panel, and then enter the new caliber you want to scale it to. Currently, it only works with millimeters and kilograms in the left-side. : Scaled up Proj. Diam (mm) : Scaled Proj. Diam (inches) : Scaled Proj. Mass (kg) Clicking on the button will automatically copy the new scaled variables over to the calculator on the left-hand side. Sub-Caliber Scaler : Starting Caliber (mm) : Ending Caliber (mm) : % Change : New Projectile Diameter (mm)
: Projectile Inital Velocity (m/sec) : ft/sec (Proj. Vel.) : MPH (Proj. Vel.) : km/hr (Proj. Vel.)	Common Initial Velocities B-17 Combat Speed - 220 MPH TAS @ 25,000 ft B-29 Combat Speed - 320 MPH TAS @ 31,600 ft SBD Dauntless Max. Dive Speed - 278~ MPH TAS Ju-87 Stuka Max. Dive Speed - 350 MPH TAS 385 m/sec (75mm KwK 37 L24 APCBC on StuG / Pz IV) 790 m/sec (76mm M1 Gun on Sherman) 935 m/sec (75mm KwK 42 L70 APCBC on Panther) 6900 m/sec (ICBM Reentry Speeds) NOTE: Heavy Bombers of WW2 rated at 89% of top speeds in Standard Aircraft Characteristics due to formation keeping needs.
: Projectile Angle of Departure (degrees) : NATO Mils (Proj. Angle of Departure) : Soviet Mils (Proj. Angle of Departure)	Common Angles of Fire/Drop 45° -- Maximum Ballistic Range 0° -- Level Bombardment/Zero Elevation -45° -- Ju-88/TBF Shallow Dive -80° -- Ju-87/SBD Steep Dive -3° to 13.5° -- 12" Guns on HMS Dreadnought -5° to 15° -- 57mm Anti-Tank Gun -12° to 25° -- 75mm Gun in M4A1 Sherman
: Projectile Fire/Drop Altitude (m) : Proj. Fire/Drop Altitude (feet) : Target Altitude (m) : Proj. Target Altitude (feet)	Common Target/Drop Altitudes 0.85m -- Chest height of average White Tailed Deer. 1.30m -- Chest height of average 1.74m tall man. 1.41m -- Turret Ring Height of Pz V Panther. 1.98m -- C1 Ariete MBT Gun Barrel Centerline. 2.13m -- Deck Height of US WWII Fleet Destroyer. 2.20m -- Panther/Tiger I Gun Barrel Centerline. 7.31m -- Armor Deck Height of Iowa-Class BB. 15.84m -- Flight Deck Height of Essex-Class CV. 487m (1,600ft) - Ju-87 Bomb/Pullout Altitude 600m -- Accepted Height of Burst for Hiroshima Bomb. 6,705m (22,000ft) - B-17/24 Bombing Altitude 10,058m (35,000ft) - B-29 Bombing Altitude 15,240m (50,000ft) - B-36/52 Bombing Altitude 24,384m (80,000ft) - SR-71/B-70 Bombing Altitude
: Projectile Form Factor G1 (Ingalls) G2 (Common in Autocannon) G5 G6 (Spitzer Bullet) G7 G8 GS (Sphere) GL (1880's Rifles) M829 (23.2 L/D Sabot) Mk 83 1000 lb LD-GP AN-M64 500 lb Hi-Drag GP Paris Gun 1918 Shell 'H'	PROJECTILE DRAG MODEL SELECTION G1 (Mach 0 to 9) (Validated to Mach 5) G2 (Mach 0 to 9) (Validated to Mach 5) G5 (Mach 0 to 9) (Validated to Mach 5) G6 (Mach 0 to 9) (Validated to Mach 5) G7 (Mach 0 to 9) (Validated to Mach 5) G8 (Mach 0 to 9) (Validated to Mach 5) KD8 (Jurens) (Mach 0.5 to 4.4) GS (Sphere) (Mach 0 to 9) (Validated to Mach 5) GL (Mach 0 to 9) (Validated in Mach 0.35 to 3.22 range) KD (Arrow) (Mach 0 to 3.987) M829 (23.2 L/D Sabot) (Mach 0 to 9) (Valid to M5.4) Mk 83 1000 lb Low Drag Bomb (Mach 0 to 5) AN-M64 500 lb Hi Drag Bomb (Mach 0 to 5) Paris Gun 1918 Shell 'H' (Mach 0 to 9) When this checkbox is selected, the last value in the Mach_Array is replaced with 60, providing a kludgey way to evaluate ballistic missile RV re-entry trajectories which begin at around Mach 25 (6.9 km/sec) at 85 km. Be sure to select the 1976 US Standard Atmosphere if you're evaluating re-entry trajectories, as well. If you deselect this checkbox, load another drag model to clear out the old model completely!

(seconds) Manually Selected Integration Interval: The smaller the number, the more accurate the table will be, but it will take longer to generate it. Automatic Integration (Super Precise - 5~m) Automatic Integration (Precise - 10~m) Automatic Integration (Moderate - 50~m) Automatic Integration (Loose - 100~m) Automatic Integration (Ragged - 250~m) The automatic integration interval adjusts the integration interval every cycle based off the projectile's velocity. You can select values according to your need. ---------------------------- (degrees) Angle Iteration Interval: The smaller the number, the more accurate the generation of various items will be, but it will take longer to generate it. 0.001 is a good balance of accuracy vs speed. Add another zero if you desire total accuracy, but be warned, it'll take longer. ---------------------------- Time of Flight: In the 1930s-40s, shipboard gunners with water cooled .50 MGs were trained to fire continuously to walk tracers onto target and the practical range for said weapons was given as approximately 1,400m; or about 4.25 seconds of flight at a 45 degree angle. BIG NOTE: German WW2 AA all had fuzes that were limited to a maximum of 30 seconds before their self-destruct features activated. The Germans in early 1945 began to switch over to contact fuzing after mathematical analysis showed this was more effective.

BALLISTIC EVALUATION MODEL: Ballistic Trajectory Evaluation: This evaluates a ballistic trajectory with the given inputs for projectile parameters at the given angle of departure. It provides you with a trajectory table in CSV format. Ballistic Range Evaluation (m) (yds) This iterates to find a ballistic trajectory that matches the distance given in the text boxes. No Trajectory table is provided at this time. Range Table (out to 5000m) This generates a range table in CSV format for 'standard' ranges out to 5000m. Intended mainly for use in direct fire (Anti-Tank) applications. Range Table (to max. range) This generates a range table in CSV format in 1 km increments from 1km to maximum range. Intended mainly for use in indirect fire (artillery/warship) applications. Anti-Aircraft Evaluation TOF (sec) This evaluates a projectile to generate CSV tables of both the maximum ballistic anti-aircraft envelope and a second anti-aircraft envelope for a given time of flight for the projectile. Form Factor Finder (m) (yds) The Form Factor Finder works by entering projectile parameters and the maximum range/angle for the projectile. It then iterates the form factor until an acceptable one is found. This is then repeated for all form factors.